There has been an explosion of new wireless technologies over the recent years such as, for instance, WiFi, Bluetooth, ZigBee, UWB, Wireless HDMI, GPS and 2G/3G/4G cellular systems. Most of these technologies have become so ubiquitous in wireless devices that availability of combined RF transmitters and receivers of different technologies within a single wireless device has become very ordinary. A challenging aspect of the further development of wireless devices is to enable these technologies to coexist in a single wireless device while being at the same time able to mitigate the interference originating from the plurality of sub-systems.
The usual practice is to measure interferences between the sub-systems with respective technologies, by using external equipment at the end of the device manufacturing process. In fact, at the RF circuit level the effects of coupling between sub-systems have to be taken into account since each sub-system is specified to tolerate some level of noise. When that level of noise is exceeded, degradation of the receiver sensitivity is experienced by the wireless device. In addition, effects of this degradation are noticeable by the end user as audible noise, throughput decrease or connection drops. This is why actions may be taken further to the measurement of interferences to attenuate the impact of coupling over the coexistence performance. Such measures, called coexistence measures, may include operations such as power decrease of a disturbing transmitter power level, data drop of on a receiver or temporary deactivation of a receiver.
Disadvantageously, the process of measurement of interferences using external equipment can be very much time consuming. In fact, this process needs to be performed for every type of wireless device assembled by the wireless device integrator. A wireless device integrator usually manages numerous product lines such that specific coexistence measures might need to be implemented for each type of wireless device. Performing such time consuming measurement operations using external equipment followed by the design of coexistence measures to mitigate noise coupling mechanisms may prove unrealistic, and sometimes they are not even performed at all.
Additionally, coexistence measures are highly dependent on the type of wireless device being measured. Indeed, the layout and components of each type of wireless device, such as filters or antennas, might be different depending on the supported communication technologies, the supported frequency bands and/or the type of antennas that are used. Therefore, the interference paths between sub-systems of respective technologies might also be different for each type of sub-system.